Science: Cheap power: as simple as ABC?: Nuclear Electric wants to build a third Sizewell station with two pressurised water reactors. Tom Wilkie reports

A COUPLE of miles along the Suffolk coast from the music festival village of Aldeburgh, a graceless structure resembling a gigantic concrete shoebox has dominated the lonely shoreline for the past 30 years.

Sizewell A, ordered in 1960, is one of Britain's first-generation nuclear power stations. Now it is no longer alone. Next door to these two elderly Magnox reactors, Britain's first pressurised water reactor (PWR), Sizewell B, is nearing completion. By this time next year, it should be at full capacity, pumping twice as much electricity into the grid as its older partner: enough for at least 1.5 million homes.

The contrasting architecture of the two stations emphasises the difference between the old and the new. Sizewell B's reactor is housed inside a double- walled dome reaching some 72 metres high - more like a cathedral for modern technology than the utilitarian cuboid of the older station.

And on that pounds 2bn dome are focused the nuclear industry's hopes for a long- term future. If Sizewell B is a success, the industry will have a case for constructing more nuclear power stations.

Brian George, the engineer who has guided Sizewell B from drawing board in 1981 to the concrete and stainless steel of today, believes the project has already demonstrated the value of nuclear power. He is now an executive director of Nuclear Electric, the state-owned nuclear generating company in England and Wales, but an engineer's pride shines through his every word. 'Sizewell B has been a watershed,' he says. 'Most reactors around the world are PWRs, and we have come into the international mainstream.'

If the construction keeps to its timetable, he expects to start loading fuel into the reactor by the end of the year, some 63 months since the first concrete was poured. 'That's fast,' he says. Even the French, who have built more than 50 PWRs with ruthless efficiency, have not managed to do it as quickly. Mr George believes that 'the old risks of construction over-runs are behind us', and expects the reactor to reach full power by the middle of 1994.

Some apologists for the nuclear industry accuse the environmental lobby of pressing for too exacting safety standards, and blame the high price of nuclear electricity on surrender to such pressure.

Not so Mr George. 'Concentration on quality and safety has assisted the fact that we built fast: there was virtually no re-work, because it's been done right first time.' As the Sizewell B design was being fleshed out between 1981 and start of construction in 1987, the rest of the world's nuclear industry felt that the UK was setting safety standards too high, he says. 'Now the rest of the world has caught up.'

He expects decisions taken for safety reasons to lead to increased performance. For example, the reactor has four independent safety control systems, which means that one can be taken out for maintenance while the reactor is running, without threatening safety margins.

But one question that could upset Mr George's tight timetable remains unresolved. The Nuclear Installations Inspectorate has not yet approved the computerised safety systems for controlling the reactor in the event of an accident. No fuel loading will be permitted until the NII is satisfied that these programs will keep the reactor in a safe condition at all times.

Already, however, Mr George is looking beyond Sizewell B. There are two possibilities. Nuclear Electric and the American company Westinghouse have put in a bid to build two Sizewell B replicas in Taiwan, an order that 'could have a very healthy UK content. Our share of the bid is worth around pounds 1bn, and Nuclear Electric would be disappointed if it did not make 7 to 10 per cent profit on that'. The Taiwanese site has space for six reactors, 'so there is excitement about the possibility of further orders', he adds.

Nuclear Electric also wants to build two more PWRs at Sizewell. Mr George believes that the average cost of power from such a twin-reactor station would be less than 3p per kilowatt hour, 'competitive with any other form of generation slated for 2001 or 2002'.

A twin-reactor station beside the first PWR would present several advantages. The existing connection to the national grid is sufficiently strong for both; and savings could be made on civil engineering services and the 'first-of-a-kind costs', such as preliminary design and validation work, already accounted for by the B station.

More than half the cost of a unit of nuclear-generated electricity arises from the need to repay capital and interest on the money borrowed for power station construction. For this reason, the price of electricity from a Sizewell C should be reasonably proofed against inflation over its 40-year lifetime. Operating and fuel costs, which will be subject to inflation, are comparatively less important for nuclear generation.)

Any investor interested in a quick buck, however, would go for combined- cycle gas turbine generating (CCGT) plants, which are cheap, fast to build and whose fuel - North Sea gas - is comparatively cheap today. Gas prices will not stay low for ever, though. 'There lies the dilemma,' Mr George says. 'How does the market balance the benefit of long-term profit from a nuclear station against the short-term profit of a CCGT station?'

The Government will have to resolve this dilemma later this year, just as fuel is being loaded into Sizewell B for the first time. When it failed in 1988 to privatise nuclear power at the same time as the rest of the electricity supply industry, the then Energy Secretary, John Wakeham, stopped all new nuclear construction pending a nuclear power review. The Government is expected to announce the extent of the review before the summer recess, and finance for Sizewell C is likely to be the most urgent issue involved.

The first-generation Magnox reactors are coming to the end of their operational lifetimes, and Mr George points out: 'If we start on Sizewell C next year, all we would do is maintain existing nuclear capacity. The country has already invested pounds 750m in first-of-a-kind costs, and this has given us a window of opportunity for export (to Taiwan).

'We have successfully transferred the technology to British companies, but if we delay too long in moving to Sizewell C, the design will become dated and, if nuclear power were to take off in five to 10 years' time, we'd be importing the technology again. The contractors who have worked on Sizewell B have earned an opportunity to show what they can do with the follow-ons. To abandon this national investment does not make sense.'